united nations mations unies
TRANSCRIPT
UNITED NATIONS MATIONS UNIES
ORGANISATION MONDIALE DE LA SANTE
EB5/83 l / 16 January 1950
ORIGINAL ! ENGLISH
NOTE ON SCHISTOSOMIASIS MNSONI
presented by Professor de Paula Souza
The sanitary and medical importance of schistosomiasis is admitted
nowadays without any doubt.
Stoll, a very well known authority, in a recent article (1947)
with the suggestive title "This Wormy World", acknowledged the world
incidence of schistosomiasis in 114 millions of persons infected by the
three schistosome parasites of man, that is Schistosoma japonicum
(46 millions), Schistosoma haematobium (39 millions) and Schistosoma
mansoni (29 millions).
The geographic distribution of S. japonicum is limited to China,
Japan, Formosa, the Philippines and Celebes Islands. S. haematobium
is distributed through all of Africa. S. mansoni is the most dispersed
of the three because it is found in equatorial Africa as well as in the
occidental hemisphere (West Indies and South America).
According to the named author, the Schistosomiasis mansoni incidence
in Africa reaches approximately 23 millions. In America the incidence
of this parasite would be some 6,200,000 cases, of which 6 million cases
are dispersed through the Brazilian north-east and 30,000 in Venezuela;
the rest of the cases being localized in the West Indies.
These numbers should be enough to show the importance of
schistosomiasis. During the last war Schistosoma japónica was the
cause of the initiation of numerous and very important investigations
of all of its aspectsî parasitologic, epidemiologic, clinical,
therapeutic and prophylatic.
, Haematobia schistosomiasis is the object of continuous research in
the areas of its occurence. Schistosomiasis mansoni interests us more
•than the other species because it is the only one that occurs in Brazil
and we can see that it has attracted the attention of many researchers
in our country as well as in other endemic areas.
W O R L D H E A L T H O R G A N I Z A T I O N
EXECUTIVE BOAFtD
Fifth Session
EB5/83 ‘ page 2
Studies carried out in Brazil show the importance of Schistosoma
mansoni as a public health problem of great geographic extent in this
country. Although we do not have complete data about the real incidence
of schistosomiasis mansoni in Brazil, all ther evidence we have indicates
not only its importance but also its progressive extension which
justifies the establishment, without loss of time < of a plan to study
and fight this ver^ important helminthiasis.
There is^ from our point of view, an opportunity^ not to be post-
poned, to co-ordinate the experience of investigators who dedicate
themselves to the study of schistosomiasis so that an efficient plan of
prophylaxis can be executed immediately^ thus preventing the situation
from assuming discouraging proportions.
Considering that the distribution and epidemiology of the
schistosomiasis mansoni requires greater knowledge than we now possess;
that the studies in relation to tlie ecology and geographic distribution
of the mollusc a intermediate host of S. mansoni call for a more
efficient study; that the diagnostic methods for S. mansoni must be
revised in accordance with more recent knowledge in this field; that
the actual therapeutics of schistosomiasis is not entirely satisfactory;
that the measures of prevention and control by the treatment of water
with substances having lethal action for the cercarlas and the
destruction of the snails b/ means of chemical substances are still in
the experimental stage; we think that the subject of the
schistosomiase needs to be recommended as a subject for larger
scientific investigations. On the other hand 5 considering that
S. mansoni should be faced as one of the most important problems of
public health in the tropics, either because of its high rate of
incidence, its great extension^ the economic value of the regions where
the disease is distributed endemically or by the severity of the lesions
caused on the victims^ the Brazilian sanitary authorities think it is
necessary to call attention to the measures of protection required for
the human element at risk. Consideration must be given to the fact
that measures available at present to fight schistosomiasis be it the
treatment of the infected individuals or the construction of publie bath
rooms and laundries, are of difficult execution due to the extreme
dissemination of the parasite and the economic and social characteristics
of the populations of the areas in the mjority of the infected countries#
Knov/ing the propitious conditions for consecutive and repeated reinfections
in these areas, the t》pe and cost of sanitary engineering constructions,
and the difficulty of putting into practice the sanitary education of ttie
EB5/83 page 3
populations infected which depends on a long period of preparation and
propaganda on the part of a great number of we11-ins true ted people^
we can perceive the complexity of the problem of the schistosomiasis..
A student of this subject, after analyzing the sanitary^ social and
economical situation of schistosomiasis in Brazil, concludes thati "it
shall be in the elevation of our economic pattern, in the diffusion of
public instruction, in the execution of general measures of urban and
rural sanitation, above all with the execution of a vigorous plan of
providing water and sewage systems in all the cities and villages of the
country that we may find a definite solution to wipe out the mansonic
parasite that at the present moment is in great progress in intensity and
extension. Unless all the measures necessary for the organization of a
hygienic canpaign are put in practice at the same time, the measures taken
will be useless and a waste of time and energy, locking over to the angle
of the gross treatment of the population, or in the combat of the molluscs,
etc. Rodrigues Silva).» All these circumstances are arrived at with
difficulty in most of the places. We think, therefore, that we should not
cross our arms in face of such an afflictive situation, abandoning
the ground, but on the contrary, giving our attention to the facts and
opinions referred to, we judge it our duty to recommend schistosomiasis
as an object for a plan for study of prophylaxis, with a view to finding
more efficient methods of combat, taking into consideration at the same
time the execution of the general measures already known and enumerated
above «
îbe World Health Organization, having in view the global problems
of schistosomiasis, should gather specialists in the subject to study
plans and measures of prophylaxis in order to reduce the incidence of this
parasite. Brazil, directly interested in this solution, would take part
in the discussion of so inp'ortant and actual a theme and would make
good use of the universal experience, learned from technicians of all the
world, for the benefit of the larger part of the rural population, and
asks the Executive Board to give all possible attention to the public
health problem involved.